1. Field of the Invention
The present invention relates to a moving object tracking method and an image processing apparatus, and more particularly to a moving object tracking method capable of continuing tracking even if an occlusion (overlapping of objects) on a video image occurs, and an image processing apparatus using the method.
2. Description of Related Art
In the case of tracking a moving object appearing on a video image, a background and a foreground are generally discriminated on the video image, and a tracking area in which the moving object to be a tracking object exists is extracted by utilizing the discrimination result. Moreover, by tracking the motion of the extracted tracking area from one frame to the next frame, the position of the moving object in the next frame is expected.
As a method of tracking a moving object appearing on a video image, for example, a KLT (Kanade-Lucas Tracker) method which tracks a feature point on a video image and is disclosed in a Non-Patent Document 1, is known. In the KLT method, a feature point is selected in the video image, and the selected feature point is tracked from one frame to the next frame by means of a gradient method, or the like.
Moreover, a Patent Document 1 discloses an image object tracking apparatus as one of conventional examples. This conventional image object tracking apparatus judges the occurrence of an occlusion in an image object area set corresponding to a moving object by comparing image object areas at the preceding point of time and at the present point of time, and thereby achieves the improvement of the precision of a tracking process.
Patent Document 1: Japanese Patent Laid-Open Application No. 2003-44860
Non-Patent Document 1: Tomasi, C and T. Kanade, “Detection and Tracking of Point Features”, CMU Tech. Rep. CMU-CS-91-132, April 1991.